The present invention relates to an improved boring tool which is suitable for machining the interior contour of a casing, such as containers or cylinders for storing a fluid under high pressures or a bomb casing, which has a single axial opening which is relatively small compared to the diameter of the casing interior which is to be machined.
Prior to the present invention the machining of the interior of such a casing with a narrow axial opening has been difficult, particularly the accurate machining of the arcuate interior immediately inside the opening.
U.S. Pat. No. 2,040,761 discloses a boring tool for machining the interior of cylinders in which the boring bar extends through the axial opening and includes a linkage which unfolds to cause the tool to pivot at the end of the boring bar outward and, through rotation of the cylinder, to cut the interior contour. The boring bar is substantially the same size as the axial opening and all movement of the boring bar is axial with all radial movement resulting from the piston operated pivoting or the cutting tool arm.
U.S. Pat. No. 3,418,884 discloses another cavity cutting machine having a tool arm mounted within the workpiece cavity with double acting pistons to control the movement of the tool arm and thus the shape of the cavity cut when the workpiece is rotated with the rotary table on which it is mounted.
U.S. Pat. No. 4,357,846 discloses a cutting tool which is designed to machine the interior of a hollow turbine shaft to eliminate any non-smooth contour which could cause a notch defect within the shaft. The tool is mounted on a rotating drive shaft and includes cam means for guiding the tool along curved trajectory.
U.S. Pat. No. 1.973,386 discloses a boring machine in which cutting tools are inserted into a hollow cylindrical container and are arranged to be driven to cut tapers or to cut a cylindrical interior surface.
U.S. Pat. No. 2,131,468 discloses a boring machine which is designed to cut tapers by utilizing a shaft mounted at an angle and a cutting tool at the end of the shaft mounted in offset position so that it is centered and will cut a preselected taper on the interior surface of the workpiece.
U.S. Pat. No. 2,517,738 discloses a taper boring head with a with a pivotally mounted arm and a cutter mounted on the arm. The taper is controlled by a system of gears, rack and pinion.